Posttraumatic Stress Disorder Among Adults in Communities With Mass Violence Incidents

Key Points Question Do adults in communities that experienced a mass violence incident (MVI) have higher prevalence of and factors associated with past-year and current posttraumatic stress disorder (PTSD)? Findings In this cross-sectional survey of a probability sample of 5991 adults living in communities that had experienced an MVI, there was a high prevalence of past-year (23.7%) and current (8.9%) PTSD. Being female, having a history of physical or sexual assault, and having a history of other potentially traumatic events were associated with the greatest risk of PTSD. Meaning These findings suggest that the outcomes of MVIs in communities extend beyond direct survivors, including persistent PTSD in many adults, and are exacerbated by exposure to prior traumatic events; thus, screening efforts for mental health services after MVIs should not focus exclusively on those directly exposed to MVIs.


Introduction
2][3] The impact of MVIs may extend far beyond directly affected survivors and their families, because ripple effects can extend to the entire affected community.Specifically, studies following the attacks of September 11, 2001 (9/11), indicated that members of the community reported high levels of PTSD following the attack.Although individuals with highest exposure to the MVI had the highest rates of PTSD, individuals with indirect exposure also reported substantial mental health concerns. 4,5e majority of findings on MVI impact on broad communities focus on a specific community or event, most commonly the 9/11 terrorist attacks 5 or school campus shootings. 6Less is known about the mental health outcomes, especially rates of PTSD, on entire communities affected by MVIs.
Previous reviews suggest that, among individuals exposed to MVI, rates of PTSD vary greatly according to demographic characteristics, level of exposure, other mental health and pre-MVI characteristics, and latency since the MVI. 1 Specifically, higher rates of PTSD following MVI exposure were seen among female individuals, low-income or unemployed individuals, and those with lower education. 1Factors specific to the MVI, including direct exposure and shorter time since the event, were also associated with PTSD. 1,7Prior exposure to potentially traumatic events (PTEs) has also been found to increase rates of PTSD among individuals exposed to MVIs. 8,9Several studies show that prior exposure to PTEs involving physical or sexual assault in particular is an important risk factor for PTSD following natural disasters, 10 exposure to toxic chemicals, 11 and new incidents of violent crime. 12This suggests it is important to examine the extent to which exposure to physical or sexual assault is associated with increased risk of PTSD following MVIs, beyond that of other PTEs.
Given the increasing rate of MVIs in the US over the past decade 13 and the major consequences associated with high rates of PTSD among individuals, it is imperative to further examine rates of PTSD among individuals residing in broad communities impacted by mass violence.Thus, this article reports survey results from a household probability sample of adults from 6 communities impacted by MVIs from 2015 to 2019.Objectives included assessing rates of PTSD (past-year and current) following MVIs across demographic characteristics (age, race and ethnicity, gender, income, and education), risk factors unrelated to the MVI (exposure to physical or sexual assault PTEs, other PTEs, and low social support), and risk factors specific to the MVI (number of months since the MVI and level of exposure).We hypothesized that individuals with prior exposure to PTEs, low social support, and higher levels of exposure to MVI would report more symptoms of PTSD.Results of this study have potential public health implications, given the substantial disease burden associated with PTSD and related mental health concerns, 14 for response and treatment needs of communities following MVIs.

Data Collection and Sample
This report follows the 11 transparency initiative disclosure elements outlined by American Association for Public Opinion Research (AAPOR) reporting guidelines. 15Data were collected sequentially between February and September 2020, with data collection for each site lasting approximately 2 months, from a household probability sample of adults living in 6 communities that PTSD Workgroup 16 (eAppendix 1 in Supplement 1).Participants completed 20 items assessing each DSM-5 PTSD symptom, as well as 2 items assessing whether symptoms have resulted in substantial distress or impairment.This measure further assesses how recently diagnostic criteria have been met

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(ie, within the past year or within the past month).Responses were aggregated and coded to determine presumptive diagnostic-level PTSD for both past-year and current PTSD (see eAppendix 1 in Supplement 1 for more details).For the present sample, α = .93.

Potentially Traumatic Events
Participants completed an 11-item measure of exposure to PTEs from the National Stressful Events Survey PTSD Module that included combat exposure, serious accidents, life-threatening illnesses, and physical or sexual assault (eg, "Has anyone ever used physical force or threats of force to make you have some type of unwanted sexual contact?").Responses to each PTE were no (0) or yes (1).
Responses were coded to create 4 groups of participants: those who had experienced (1) physical and sexual assault PTEs, (2) other PTEs, (3) both physical and sexual assault PTEs and other PTEs, and (4) no history of any PTEs.

Social Support
Participants completed 5 items from the Medical Outcomes Study module assessing the social support they received in the past 6 months (eg, "How often was someone available to confide in or talk about your problems?") 17(eAppendix 1 in Supplement 1).Responses had a 4-point scale, ranging from 1 (none of the time) to 4 (all of the time).Higher scores on this measure (range, 5-20) have been associated with lower levels of psychological distress, with a score of 15 or lower indicating low social support.Numerous studies have used this measure, including studies of the 9/11 terrorist attacks 4 and hurricanes in Florida. 16,18In the present sample, α = .91.

Latency
The length of time since the MVI was calculated by subtracting the survey completion date from the date of the MVI.Latency is reported in months.

Exposure to the MVI
Participants completed 12 items assessing their level of exposure to the MVI specific to their community (eg, "You personally were shopping or working at the Walmart Supercenter near the Cielo Visto Mall in El Paso, Texas when the shooting happened," or "You were the parent, guardian, other relative, or close friend of a student or worker who was at Marjory Stoneman Douglas High School the day of the shooting").Responses to items were coded to indicate whether participants had high levels of exposure (0 = no, 1 = yes) to the MVI defined as either they or a close friend and/or family member was on site during the shooting.

Demographic Characteristics
Participants completed self-report items assessing their demographic characteristics (eg, gender, race, and ethnicity).Data on race and ethnicity are included in this study to provide valuable information regarding potential difference in MVI impact among subgroups.

Statistical Analysis
Data analysis was performed from September to November 2023.To examine our hypotheses, we conducted univariate comparisons to examine between-group differences in the prevalence of pastyear and current PTSD across demographic characteristics (age, race and ethnicity, gender, income, and education), risk factors unrelated to the MVI (exposure to PTEs and low social support), and risk factors specific to the MVI (short latency since the MVI and high levels of exposure).The threshold for statistical significance was 2-sided.Next, we simultaneously entered the demographic characteristics, risk factors unrelated to the MVI, and risk factors specific to the MVI into logistic regression analyses to assess which variables were uniquely associated with PTSD after accounting for the other variables in the model.We ran separate models for past-year and current PTSD.
All analyses were weighted to adjust for potential nonresponse bias by first weighting to adjust for household size and likelihood of household nonresponse and then using iterative proportional fitting to align with population benchmarks on gender, age, education, race, ethnicity, and stratum.
The weighting parameters were based on the US Census Bureau's 2018 American Community Survey 5-year estimates.The weighted demographics matched or were very close to all Census benchmarks for each community.See eAppendix 2 and eTable 2 in Supplement 1 for more detail.
Analyses were conducted using SPSS statistical software version 28 (IBM).A missing values analysis indicated all items had less than 5% missingness, and preliminary examination of our regression model indicated 10% missing cases; therefore, we conducted available case analysis.A sensitivity power analysis indicated that with 10 independent variables, α = .05,and our most conservative sample of 5402 participants, power exceeded 0.99 to detect small effect sizes (f 2 = 0.02).

Descriptive Statistics
Invitations were mailed to 110 289 addresses in 6 communities that had experienced an MVI.A total of 6867 adults aged 18 years or older accessed the website with a description of the study and consent materials.Of these, 5991 (87.2%) agreed to participate and completed the survey (response rate, 5.4%), 343 (6.3%) partially completed the survey, and 443 (6.5%) did not meet eligibility criteria or refused to participate.Among the final sample of 5991 respondents, most were female attainment were associated with both past-year and current PTSD prevalence.Among the risk factors unrelated to the MVI, exposure to both physical or sexual assault and other PTEs and low social support were also associated with increased risk for past-year and current PTSD.Participants reporting high levels of MVI exposure were also more likely to experience past-year and current PTSD.Shorter latency since the MVI was only associated with past-year PTSD.

Logistic Regression Analyses Examining PTSD Prevalence Risk
We simultaneously entered the factors potentially associated with PTSD into logistic regression analyses (

Discussion
The findings of this survey study confirm a high prevalence of exposure to PTEs, PTSD, and risk factors for PTSD among communities affected by MVIs.Using the diagnostic criteria for PTSD, nearly one-fifth (19.0%) of community members had experienced a Criterion A level of exposure to the MVI (ie, either they or a close friend and/or family member was on site during the shooting).Regarding PTSD prevalence, approximately 1 in 4 individuals met criteria for past-year and 1 in 10 for current PTSD diagnosis, far exceeding past-year PTSD prevalence of 4.7% among US adults. 16,19Rates of current PTSD were lower than rates of past-year PTSD, which is consistent with research showing  20 Among studies of direct survivors of MVIs, PTSD prevalence rates range from 9% to 91% 1 ; our findings provide important perspective on the broader impact of MVIs measured by PTSD among members of the larger community.
The present findings also have important implications for identifying those at most risk for developing PTSD following MVIs.Specifically, we found that individuals who are younger, are female, have low social support, have experienced a higher number of PTEs, and have a history of physical or sexual assault were more likely to have PTSD.These findings are consistent with literature on PTSD risk factors in the context of PTEs, 19 including MVIs. 21Decades of research have found that female individuals are more vulnerable to PTSD than male individuals. 22Reasons for this remain unclear, but it may be due to female individuals having higher rates of physical and sexual assault, greater vulnerability to the impact of stressors for biological or psychosocial reasons, or a greater willingness than male individuals to disclose symptoms.Our exploratory analyses highlight the importance of

Measures Prevalence of Past-Year and Current PTSD
Posttraumatic Stress Disorder Among Adults in Communities With Mass Violence Incidents

Table 2 .
Differences in demographic characteristics across PTSD prevalence are presented in African American, 1328 (25.6%) were Hispanic, and 441 (7.8%) identified as other races and ethnicities (eg, biracial, Jamaican, Caribbean, Taino, North African, Middle Eastern, or Jewish).Latency, or time since the MVI, ranged from 8 to 56 months (mean [SD], 18.94[11.61]months).Less than 3.0% of participants (160 participants) reported they were personally on site and 19.0% (1136 participants) reported a close friend and/or family member was on site at the MVI, resulting in 21.0%JAMA Network Open | Psychiatry

Table 3 .
See additional descriptions of PTSD prevalence across variables in eTable 3 in Supplement 1.Among the demographic characteristics, being younger, being female, and reporting lower annual household income and educational

Table 4 )
. Results indicated that younger age, female gender; lower income; experiencing either physical or sexual assault, other PTEs, or both physical or sexual assault and other PTEs; lower levels of social support; and high exposure to the MVI were each uniquely associated with both past-year and current PTSD.Specifically, for past-year PTSD, being female (odds ratio [OR], 2.32; 95% CI, 2.01-2.68),experiencing a history of both physical or sexual assault and other PTEs (OR, 9.68; 95% CI, 7.48-12.52),and high levels of exposure to the MVI (OR, 1.66; 95% CI, 1.40-1.96)were associated with the largest proportions of explained variance.Similarly, for current PTSD, being female (OR, 2.20; 95% CI, 1.77-2.73),experiencing a history of both physical or sexual assault and other PTEs (OR, 16.54; 95% CI, 9.53-28.72),and high levels of exposure to the MVI (OR, 1.82; 95% CI, 1.45-2.28)were associated with the greatest relative risk for current PTSD.Sensitivity analyses examining the regression models within each community indicated that female gender, experiencing a history of both physical or sexual assault and other PTEs, and social support were associated with PTSD across each community.

Table 2 .
Correlations Among Study Variables a rates of PTSD decrease over time for several reasons including normal recovery, improvement in a sufficient number of symptoms to no longer meet full criteria, or receiving successful treatment.

Table 3 .
Prevalence of Past-Year and Current PTSD Across Study Variables Additional details on the assessment of posttraumatic stress disorder (PTSD) eAppendix 2. Additional details on the sampling strategy, data collection method, and weighting eTable 1. Response rate and mode of survey completion across communities eFigure 1. STROBE flowchart for sample selection eTable 2. Comparison of benchmark population parameters to sample distribution eFigure 2. Prevalence of PTSD across community eTable 3. Demographic characteristics across PTSD prevalence eReferences